Hemiaster, AGASSIZ et DESOR, 1847

Richard Pokorný, Jaroslav Kaše, Jiří Kvaček, Kamil Zágoršek, Kočí, Tomáš & Žítt, Jiří, 2012, Fossils In Late Cretaceous To Early Palaeocene Flint Nodules Embedded In Pleistocene Glaciofluvial Sediments Near Fukov (Děčín District, Northern Bohemia), Acta Musei Nationalis Pragae Series B 68 (3 - 4), pp. 119-131 : 123

Hemiaster (?) sp.

Pl. 3, fig. 2

M a t e r i a l: Dorsal part of 1 test, collection number FZP/P/12/2-3/022.

D e s c r i p t i o n: Apical system unpreserved, ambulacra differentiated as for their function. The posterior paired petals shorter than the anterior ones, the anterior petals distally closing. Pores in pore-pairs rather elliptical than circular. Anterior ambulacrum non-petaloid, very shallow, plates short and wide, pore-pairs uniserially arranged. Interambulacral plates large, tubercles unpreserved. Fasciola unpreserved.

R e m a r k s: The specimen most probably represents an internal cast of the test in which no external structures are preserved. Because of this unfavourable type of preservation, the most taxonomically important features are missing (number of gonopores, fasciolae). The overall character of the single test indicates a relationship to some species of Hemiaster AGASSIZ et DESOR, 1847 . The affinity to some other echinoid taxa, e.g. hemiasterids Bolbaster POMEL, 1869 or Proraster LAMBERT, 1895 is not probable (cf. Kahlke, Neumann and Taake 2009). Bolbaster is dorsally more convex and Proraster has dorsally very deep anterior sulcus ( Smith and Kroh 2011).